Culturable bacteria from an Alpine coniferous forest site: biodegradation potential of organic polymers and pollutants

Abstract

The potential of the culturable bacterial community from an Alpine coniferous forest site for the degradation of organic polymers and pollutants at low (5 °C) and moderate (20 °C) temperatures was evaluated. The majority of the 68 strains belonged to the phylum Proteobacteria (77%). Other strains were related to Bacteroidetes (12%), Alphaproteobacteria (4%), Actinobacteria (3%), and Firmicutes (3%). The strains were grouped into 42 different OTUs. The highest bacterial diversity was found within the phylum Bacteroidetes. All strains, except one, could grow at temperatures from 5 to 25 °C. The production of enzyme activities involved in the degradation of organic polymers present in plant litter (carboxymethyl cellulose, microgranular cellulose, xylan, polygalacturonic acid) was almost comparable at 5 °C (68%) and 20 °C (63%). Utilizers of lignin compounds (lignosulfonic acid, lignin alkali) as sole carbon source were found to a higher extent at 20 °C (57%) than at 5 °C (24%), but the relative fractions among positively tested strains utilizing these compounds were almost identical at the two temperatures. Similar results were noted for utilizers of organic pollutants (n-hexadecane, diesel oil, phenol, glyphosate) as sole carbon source. More than two-thirds showed constitutively expressed catechol-1,2-dioxygenase activity both at 5 °C (74%) and 20 °C (66%). Complete phenol (2.5 mmol/L) degradation by strain Paraburkholderia aromaticivorans AR20-38 was demonstrated at 0–30 °C, amounts up to 7.5 mmol/L phenol were fully degraded at 10–30 °C. These results are useful to better understand the effect of changing temperatures on microorganisms involved in litter degradation and nutrient turnover in Alpine forest soils.

Biodegradation Potential and Putative Catabolic Genes of Culturable Bacteria from an Alpine Deciduous Forest Site

“…The second predominating genus with 14 representatives was Collimonas ( Gammaprotebacteria ), the majority of them were clustered in the second largest OTU (OTU02, twelve strains). Both genera are known for various cold-adapted representatives [ 22 , 40 , 41 , 42 ], the production of cold-adapted enzymes and low-temperature degradation of organic compounds [ 42 , 43 ]. Among the 55 strains, no Alphaproteobacteria and only a very low fraction of Bacteroidetes (six strains) and Gram-positive representatives (four strains) were detected.…”

“…Among the 55 strains, no Alphaproteobacteria and only a very low fraction of Bacteroidetes (six strains) and Gram-positive representatives (four strains) were detected. The latter can be related to lower competitiveness compared to Gram-negative bacteria [ 42 ]. The low biodiversity might be a result of site-specific soil conditions, characterized by lower contents of soil organic matter and soil nutrients compared to a previously studied Alpine coniferous forest site [ 42 ].…”

Production and partial characterization of a crude cold-active cellulase (CMCase) from Bacillus mycoides AR20-61 isolated from an Alpine forest site

“…In an earlier study (Berger et al 2020), we demonstrated the ability of a high number of bacterial strains isolated from soil from an Alpine coniferous forest site to produce CMCase. Among the 68 tested strains, Bacillus mycoides AR20-61 was the best enzyme producer and was therefore selected for further studies on CMCase production and enzyme characterization.…”

“…The bacterial strain used in this study was isolated from soil from an Alpine coniferous forest site (46°35′ 16.2″ N, 11°26′ 4.9″ E) located 7 km north of Bozen/Bolzano, Italy, below the Rittner Horn at an altitude of 1724-1737 m above sea level (França et al 2016) and identified as member of the species Bacillus mycoides (GenBank accession no. ACU01000002; Berger et al 2020). The strain was stored at − 80°C using ROTI©Store cryovials.…”

Isolation and Characterization of Strain Exiguobacterium sp. KRL4, a Producer of Bioactive Secondary Metabolites from a Tibetan Glacier

“…By contrast, alpine habitats are at the very beginning of exploration and bioprospecting for NPs producers [ 14 , 15 ], and a few recent studies have highlighted the high microbial diversity present in these extreme habitats, encouraging the isolation and exploitation of alpine bacteria for biotechnological purposes [ 16 ]. Several studies reported the bioremediation potential of alpine microorganisms, their antioxidant, photoprotective activities through the production of pigments [ 17 , 18 ] and the potential for NPs discovery [ 19 , 20 ]. The Qinghai-Tibet Plateau, often called the ‘world’s roof’ or ‘the third pole’ is located in the southwest of China and is the highest and largest region with permafrost in the world.…”